This projects will look at the correlation between glutathione concentrations in cells and radiation survivability. A fluorescence assay for glutathione levels in cells has been developed. However, it is desirable to determine the glutathione concentrations in cells. Experiments will be carries out on the NFCR multilaser system that is capable of measuring cell volume along with glutathione levels. The ratio of the two measurements will give actual concentrations. The goal is to sort cells with high and low concentrations of glutathione to determine whether there are differences in their radiation survivability.